1. Field of the Invention
The present invention relates generally to the field of patterned structures used in semiconductor devices, and more particularly to a method for fabricating fin-shaped structures with equal widths.
2. Description of the Prior Art
Field effect transistors are important electronic devices in the fabrication of integrated circuits. As the sizes of the semiconductor devices becomes smaller and smaller, the fabrication of the transistors also has to be improved so as to fabricate transistors with smaller sizes and higher quality.
With the increasing miniaturization of the semiconductor devices, various multi-gate MOSFET devices having fin-shaped structures have been developed. The multi-gate MOSFET is advantageous for the following reasons. First, the manufacturing processes of the multi-gate MOSFET devices can be integrated into the conventional logic device processes, and thus are more compatible. In addition, since the three-dimensional (3-D) structure of the multi-gate MOSFET increases the overlapping area between the gate and the substrate, the channel region is controlled more effectively. This therefore reduces the drain-induced barrier lowering (DIBL) effect and the short channel effect.
Generally, the fin-shaped structures of the multi-gate MOSFET cannot be defined directly through conventional photolithography processes. Thus, an auxiliary process, such as a sidewall image transfer (SIT) process is often adopted by the semiconductor manufacturers to define these fin-shaped structures. However, there is still a drawback resulting from the SIT process. For example, the fin-shaped structures within different regions, such as logic regions and memory regions, often have different widths due to different pattern densities. The variations in the widths of the fin-shaped structures adversely affect the performance of the transistors in these regions. Therefore, there is still a need to provide a method for fabrication patterned structures of semiconductor devices in order to overcome the above-mentioned drawback.